Multiple-screw jack



J. CORYELL.

MULTIPLE SCREW JACK.

APPLICATION FILED AUG-l3, 1920.

Patented Nov. 8, 1921.

Jami-07 Jbhn C'or ye ZZ,

UN [TE-D STATES PATENT OFFICE.

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Application, filed August 13, 1920. Serial No.

To all whom it may conoem:

Be it known that I, JOHN CORYELL, a citizen of the United States, residing at Detroit, in the county of Wayne and State of ichigan, have invented a certain new and useful Improvement in Mutiple-Screw Jacks, of which the following is a specification.

his invention relates to multiple screw.

which one screw rotates or telescopes inside the other. The object of the invention is to operate such a jack by continuous rotary movement and to do it in such a manner that the jack operates comparatively rapidly butwith great power and over a comparatively great distance or height whereby the device is especially applicable for heavy work such as in connection with heavy trucks, and in other places as in factories where heavy loads are to be lifted. The invention consists in a novel combination of parts obtaining the foregoing and other objects which can be easily and comparatively cheaply made, which is satisfactory in use and is not readily liable to get out of order. More particularly the invention consists in many features and details of construction hereafter more fully set forth in the specification and claims.

eferring to the drawings in which similar numerals represent the same parts throughout the several views,

igure 1 is a vertical sectional detail view of mechanism illustrating this invention in its I{preferred form.

ig. 2 is a detail 2-2 of Fig. 1.

Fig. 3 is a reduced scale on the line 33 of Fig. 1.

The jack is supported upon a suitable base 10 having a foot 12 of ordinary construction adapted to rest upon the floor. The side of this base 10 is preferably provided with a convenient handle 14 by which the entire mechanism may be conveniently transported b the operator who takes hold of the handle. l elescopically mounted on the base 10 and guided for vertical movement only thereon by the handle 14 and the guide screw 16 entering suitable slots 17 and 19 respectively is a hollow case 18 preferably made of two parts, the upper one 18 being a cover readily detachably securable in one or more securing screws 20.

The base 10 is vertically bored to receive the external or lower screw 22 whose outer jacks of the type in plan view on the line detail plan view devices, such as set Specification of Letters Patent.

normal position by Patented Nov. 8, 1921. 403,231.

'circumferenceis provided with screw threads 24 mtermeshing with other threads 26 a worm 30 carried by a shaft 32 rotata le by application of a wrench or other tool to its non-circular end 34 readily accessible to the operator.

T e upper cover member 18 is perforated in alinement with the axis of the screw 22 and the opening is closed b a bearing plate 36 detachable secured in pliice by any suitable means as 38. This bearing plate 36 is vided with an opening 40 of sufficient size so that internal or upper screw 42 can freely pass down through as shown in Fig. 3.

his screw 42 which also telescopes in screw 22 is provided along its length with a keyway 44 slidably entered by a key 46 mounted in the perforation 40 of plate 36. This will be referred to as a spline connection. This screw 42 is provided with screw threads 48, of opposite pitch from the screw threads 24 on the outside of the outer screw 22, engaging internal screw threads 50 cut on the inside of screw 22.

The result of the foregoing construction is that when the operator rotates shaft 32 he causes the worm 28 to rotate the outer screw 22 in one direction and that as the upper screw 42 is, through threads 4850, threaded into it in the opposite direction, and that as screw 42 is held against rotation b the. key 46, screw 42 tudina ly with reference to the outer screw 22 as well as along with it inthe same direction. The ultimate result is that the speed of lifting or lowering, as th case may be, is, assuming the pitches of both sets of screw threads are the same, double of what it would e were only one screw used and the height of lift or lower is correspondingly increased.

The upper end of screw 42'carries the load engaging block 52. As the screw 42 does not rotate this block is referabl pinned to it. s soon as the load lifting ead 52 engages the load which has to be lifted, it through the agency of pin 54, holds the screw 42 against rotation and thus relieves the strain which would otherwise exist at the key 46.

The base and case are each non-rotatable and will be referred to an non; rotatable members.

Having thus described my invention what in turn promembers, one of which is a base, a pair of non-rotatable member,

' bers with screws telescoping with each other and with the non-rotatable members, screw threads between said screws, other reversely pitched screw threads between one screw and one non-rotatable member, a spline connection between the other screw and the other non-' rotatable member, and means for rotating the rotatable screw.

3. In mechanism of the class described, the combination of two separated non-rotatable members one of which is a base, means permitting reciprocation of one of said members with reference to the other, a pair of screws telescoping with each other and with the non-rotatable members, screw threads between said screws, other screw threads be: tween one screw and one non-rotatable member, a spline connection between the other screw and the other non-rotatable member, and means inclosed within one of said nonrotatable members for rotating the rotatable 4. In mechanism of the class described, the

combination of two separated non-rotatable members one of which is a base, means permitting reciprocation of one of said memreference to the other, a pair of screws telescoping with each other and with the non-rotatable members, screw threads between said screws, other reversely pitched screwthreads between one screw and one a spline connection between the other screw and the other nonrotatable member, and means inclosed within one of said non-rotatable members for rotating the rotatable screw.

5. In mechanism of the class described,the combination bf a base, one screw threaded into the basefa second screw inside the'first screw threaded therein, the screw threads between the base and the first screw being in one direction and the other set of screw threads being. in the opposite direction, means holding the second screw against rotation while permitting it to reciprocate to andfrom the base, and means for rotating the first screw, for the purposes set forth.

6. In mechanism of the class described, the

threads one screw threaded screw inside the first the screw threads being in combination of a base, into the base, a second screw threaded therein, between the base and the first screw one direction and threads being in the opposite direction, a case member for the screws mounted for reciprocation with reference to the base, and means for preventing rotation of the case member durin such reciprocation, operating means for t e first screw inside said case, and means on said case holding the second screw against rotation while permitting it to reciprocate through thecase to and from the base, for the purposes set forth.

7. In mechanism of the class described, the combination of a base, one screw threaded into the base, a second screw inside the first screw threaded therein, the screw threads between the base and the first screw being in one direction and the other set of screw threads being in the opposite direction, a

case member forthe screws mounted for reciprocation with reference to the base, and means for preventing rotation of the case member during such reciprocation, worm gear operating means for the first screw in side said case operatable from outside the case, and means on said case holding the second screw against rotation while permitting it to reciprocate through the case to and from the base, for the purposes set forth.

8. In mechanism of the class described, a base member suitable for standing upon a support, a screw threaded into a vertical opening in the base for movement with reference thereto, a second screw inside the first and engaging the same in screw threads of opposite pitch from the threads between the first screw and base, a worm gear mechanism at the upper end of the first screw for operating it, a supporting case for said worm gear mechanism traveling with the gear mechanism and the first mentioned screw to and from the base, pin and slot connections between the case and the base permitting its reciprocation with reference to the base, preventing its rotation with reference to the base, a spline connection between the reciprocating case and the second screw permitting reciprocation of the second screw, with reference to the case and base, for preventing its rotation with reference thereto, and a load carryinj cap rigidly attached to the upper end of t esecond screw, for the purposes set forth.

In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

JOHN CORYELL.

Witnesses:

DWIGHT B. Cnnnvnn, ANNA RosnNrnAL.

the other set of screw- 

